As if Amy Winehouse didn't have enough problems, she has now been condemned by the United Nations.

Speaking out against "coke-snorting fashionistas", UN drug tsar Antonio Maria Costa described Winehouse as "the poster girl for drug abuse".

It is all to do with a controversial report by the UN's prohibitionist-leaning International Narcotics Control Board, which attempts to link "celebrity endorsement of drug related lifestyles" to the boom in European cocaine consumption and devastation being wrought in Africa as new drug-smuggling routes open up. Costa claimed "one song, one picture, one quote that makes cocaine look cool can undo millions of pounds worth of anti-drug education and prevention".

Costa's accusations are not based on statistical research. Rather it is an intuitive notion that celebrities are role models who influence social behaviour. And, by singling out Winehouse, Costa focuses his ire on the strand of celebrity culture most frequently accused of corrupting the young and impressionable.

Popular music and drugs have been linked by a century of rebellious counter-cultural attitudes and a predilection to hedonism (probably endemic in any medium whose roots are in social dancing). There is an undeniable link between alcohol and the blues, marijuana and jazz, LSD and psychedelic rock, cocaine and disco, speed and punk, weed and reggae, crack and rap, ecstasy and house music, with the disturbing spectre of heroin lurking behind many of pop culture's edgiest and often most tragic figures.

A study published last month by the University of Pittsburgh School of Medicine claimed that one third of the most popular songs in America (based on analysis of the 2005 Billboard charts) mentioned substance abuse of some kind. The worst-offending genre, predictably, was hip hop. Mind you, those who would censure music might be surprised to learn that it was closely followed by country and western. Only four songs (all in the rock genre) contained specific messages against substance abuse.

Although the study was careful not to draw conclusions regarding exposure to lyrics and social behaviour, Costa (executive director of the UN Office on Drugs and Crime) has been more forthright. "Amy Winehouse might adopt a defiant pose and slur her way through Rehab, but does she realise the message she sends to others who are vulnerable to addiction?"

Personally, I am not sure if Winehouse makes a very good poster girl for drug abuse. Photographed emaciated, bruised and bleeding, weeping over her jailed husband, slurring onstage, cancelling shows, her closely (and somewhat salaciously) documented journey from pop princess to barely functioning addict seems more like a cautionary tale.

Girls, do you want to wind up scruffy, scrawny and toothless? Just say yes. Certainly, she has fame, which seems the primary aspiration of a huge section of the young population, but few would deny that it was based on her exceptional talent.

Back to Black was a hit before anyone knew the extent of Winehouse's problems. She may have sung "No, no, no" to rehab, but the celebratory defiance of that line was surely tempered by news that she has been in and out of rehab ever since.

Winehouse's story is a tragedy unfolding and has largely been reported as such. Like Billie Holiday or Janis Joplin, exceptional singers who struggled with addiction in less media-saturated times, Winehouse is a poignant figure, whose intensity of expression and tendency towards self-destruction seem psychologically linked. I suspect you would have to be particularly ill-tuned to popular culture to think she is an aspirational figure.

There is nothing new in any of this, which makes it all the more curious that the UN has finally decided to weigh in. When it comes to poster stars for drug abuse, Keith Richards (at 63, a contemporary of Costa's) is surely the daddy of them all.

Unlike Winehouse, Richards is widely viewed as a kind of heroic figure, as much for surviving decades of being utterly stoned as anything else. Such is his iconic status, old leather-face is currently appearing in a Louis Vuitton advertising campaign, seated next to a piece of designer luggage. Frankly, it is hard to tell which one is supposed to be the suitcase.

They should circulate that picture around schools - kids, this is what a lifetime of drugs will do to you. Even Keith says no these days.

Indeed, he was recently heard suggesting that Winehouse "should get her act together", perhaps overlooking the fact that it took him nearly two decades to kick heroin, and (I can testify from having spent some very enjoyable time in his company) he remains a heavy drinker.

But there are serious issues here. Pop culture has a strong relationship with drugs, so should its participants bear moral responsibility for the behaviour of their mass audience? With the stiff discomfort of a patrician trying to get down with the kids, Costa quoted lyrics from the JJ Cale/Eric Clapton blues classic Cocaine, before concluding: "If you don't care what cocaine can do to you, at least take responsibility for how it can damage the lives of others."

Yet his example demonstrates the over-simplification of the whole argument. Cocaine is not a straightforward anti-drugs anthem but a song of great ambivalence, at once enamored and fearful of the narcotic high. And Clapton rose up through the acid-fuelled psychedelic rock boom, becoming a full-blown alcoholic and heroin addict, before getting sober at the age of 46 (Winehouse is still only 24).

Now Clapton owns a rehab clinic and counsels fellow addicts. He is full of regret for his past, yet there are those who would suggest his latterday music has never touched the heights of his early, narcoticised offerings.

In pop culture in particular there has been, perhaps, a dangerous notion that drugs fuel creativity. Yet it is impossible to deny that some of the greatest music ever made was, at the very least, influenced by drug culture.

The Beatles are still venerated as the greatest band ever (and are often held up as role models for their peace politics), yet they are also one of the most drug-saturated bands in pop history, from the psychedelic highs of Sgt Pepper to the brutal lows of John Lennon's Cold Turkey.

Many others, of course, never took drugs in their lives (or certainly never openly embraced them). Rock heroes such as Frank Zappa and Bruce Springsteen have been outspoken against drugs. For every defiant anthem of Sex and Drugs and Rock and Roll ("is all my brain and body needs" to quote Ian Dury's somewhat tongue-in-cheek contribution to the debate) there is a comedown song such as Neil Young's quietly moving Needle and the Damage Done. And, for every iconic drug survivor such as Keith Richards, there is a Jimi Hendrix extinguished in their youth in the most pathetic circumstances imaginable.

Pop culture doesn't tell one story about drugs, it tells all kinds of stories, reflecting society as much as shaping it. We don't know the end of Amy Winehouse's story yet, but it would be simplistic to suggest that there is only one possible moral conclusion to be drawn.

The UN drug tsar insisted: "If Miss Winehouse advertised fur coats or blood diamonds, there would be a backlash. Yet when she is the poster girl for drug abuse, nobody seems to care."

But actually, a lot of people care. They care about her music. They care about her well-being. They just don't see the fate of nations hanging on whether she makes it through rehab or not.